Fereshteh Kunkel earned a Bachelor’s of Arts degree from the University of New Mexico, with a double major in Communication Disorders and Spanish. During her undergraduate studies, she learned American Sign Language and spent a summer research internship at Gallaudet University. She received a master’s degree in Communication Sciences and Disorders at the University of Texas at Dallas and completed her Clinical Fellowship Year serving monolingual English and Spanish-speaking elementary and middle school students. After completing research on the English, Spanish and Bilingual lexical development of Spanish-English speaking preschoolers, Fereshteh was awarded a Ph.D. in Communicative Sciences and Disorders from the University of Texas at Dallas. Currently, she works for Bilingual Therapies as a bilingual clinician evaluating and providing speech and language therapy in Spanish, Persian and English to young children in San José, California.

The purpose of December’s blog is to introduce clinicians to the vocabulary checklist of the MacArthur-Bates Communicative Development Inventory: Words and Sentences English and Spanish form and to discuss how this tool is used to calculate a Bilingual score, otherwise known as a total conceptual score. Before discussing the organization and norming of the inventory, a definition and overview of the lexicon as well as a general description of English, Spanish, and Bilingual lexical development will be given. Finally, a summary and discussion of the questionnaire and other relevant information will be provided.

The lexicon or productive vocabulary is often defined as the “mental dictionary.” The lexicon is the earliest reflection of a child’s knowledge of language because it precedes multi-word combinations and syntax (Pearson, 1998). It is also fundamental to language learning and use because it serves as a building block for other linguistic domains (Bassano, Maillochon, & Eme, 1998; Kirk & Pisoni, 2000). Since productive vocabulary can be used to predict language delay, and since with age and language experience there is parallel growth of lexical abilities (Pearson, 1998), studies of this linguistic domain are timely, especially for the bilingual population. Additionally, vocabulary scores are strongly associated with general cognitive and academic skills, with a high correlation between vocabulary and intelligence, and with other language behaviors associated with school related tasks (Pearson, 1998). Research has demonstrated that Spanish monolingual development resembles that for English in rates and patterns of lexical production (Hernandez-Pina, 1979; Peraita, 1986) and that bilingual acquisition utilizes analogous linguistic systems as monolingual development, and proceeds in a comparable sequence (De Houwer, 1995) and rate as in monolingual children (Patterson, 2004; Pearson, Fernandez, & Oller, 1993). However, researchers such as Pearson et al. (1993) also emphasize that failure to measure both languages in the bilingual’s lexicon would significantly undervalue their productive vocabulary skills. It is precisely for this reason that clinicians should establish the linguistic milestones for their bilingual population using appropriate tools, such as the English and Spanish MacArthur Bates Communicative Development Inventory, so that an accurate evaluation of the student’s lexical development can be established and intervention can be provided when benchmarks are not met (De Houwer, 1995; Pearson, 1998).

The MacArthur-Bates Communicative Development Inventory “Words and Sentences” (CDI) form (Fenson et al., 1993) is a parent questionnaire commonly used to measure the productive vocabulary of English-speaking children ages 16-30 months old. The vocabulary portion consists of 680 words organized into 22 semantic categories (e.g., animals, toys, and food) and syntactic categories including nouns, verbs, and adjectives (Fenson et al., 1993). It was normed on a large population of monolingual English-speaking children, representing a socioeconomic status that was higher than the national average based on 1990 U.S. census information. The Inventario del Desarrollo de Habilidades Comunicativas “Palabras y Enunciados” (IDHC) (Jackson-Maldonado et al., 2003) measures the productive vocabulary of Spanish-speaking children ages 16-30 months old. It consists of a 680-word Spanish productive vocabulary checklist organized into 23 categories. The Spanish IDHC has one more lexical category than the English CDI since “preposiciones/artículos” and “locativos” are split into two separate categories, instead of one category (“prepositions/locations”), as in the English form. Although the format of the inventories is similar for the English and Spanish questionnaires, the IDHC is not simply a translation of the CDI, since it was developed with consideration for the cultural and linguistic variations of Mexican Spanish (Jackson-Maldonado et al., 1993). In addition, it was normed on a large group of monolingual Spanish-speaking toddlers of a higher socioeconomic status than the national average. Thus, caution is advised when interpreting data for children whose socioeconomic profile does not closely match that of the norming group (Jackson-Maldonado et al., 2003). For both the English CDI and Spanish IDHC, parents simply mark on the questionnaire those words that their child currently produces from the list of words organized by lexical category (e.g., clothes, body parts). This format decreases the potential for invalid estimates of productive vocabulary since adults do not have to rely solely on their memory for the words their child produces (Pearson, 1998; Pearson & Fernandez, 1994). A single-language vocabulary score can then be calculated by tallying the total number of words marked on the vocabulary checklist out of a possible 680, which represents the total number of words produced in each language individually.

A Bilingual, or total conceptual score, is derived from a list developed by Marchman (1999) of the conceptual matches between the English and Spanish form. The Bilingual score is necessary since bilingual children’s productive vocabulary is distributed across two languages. This score, therefore, not only accounts for overlapping words between English and Spanish but also those words used in one language that are not used in the other. Using a single language score exclusively would neglect a significant portion of bilingual children’s productive vocabulary, thus underestimating lexical knowledge (Pearson et al., 1993). Although the Bilingual score is calculated based on the verbal labels for concepts on the CDI and IDHC, it does not simply represent a summation of English total vocabulary and Spanish total vocabulary scores. Instead, the Bilingual score reflects the following guidelines: (1) a concept has more than one verbal label in English (e.g., chicken, hen) but only one label in Spanish (e.g., gallina), (2) a concept is represented in only one of the languages (e.g., rooster), or (3) a concept has multiple labels in both English (e.g., sofa, couch) and Spanish (e.g., sofá, sillón). The Bilingual score, therefore, represents the number of concepts expressed regardless of language.

In summary, clinicians working with bilingual children can use the MacArthur Bates Communicative Development Inventory to establish the English, Spanish and Bilingual lexical skills of their students. Since lexical development is important to later language learning, tools such as the Communicative Development Inventory “Words and Sentences” and the Inventario del Desarrollo de Habilidades Comunicativas “Palabras y Enunciados” can be used to determine a child’s present level of communication while also taking into consideration their language skills as a whole. The inventories have been adapted to other languages, including Chinese, American Sign Language, and dialects such as Cuban Spanish, among others, so that clinicians who work with children that speak languages other than Spanish can measure the lexical skills of their clients. In addition to the long forms described here, short forms are available as well as a new CDI III form for children ages 30 to 37 months. Clinicians are encouraged to visit the MacArthur Bates Communicative Development Inventories website for further details and information (e.g., the list of matched concepts for calculating the bilingual score) including ordering the questionnaire and accompanying manual (visit www.sci.sdsu.edu/cdi/).